1. Technical Field
The invention relates to a measuring device for measuring raised areas on the sidewalls of pneumatic tires. More particularly, the invention relates to a very simple lightweight measuring device which automatically indicates the height of a projection on the inside or outside of the sidewall of a pneumatic tire by engagement of a sliding scale engaging the projection.
2. Background Information
Pneumatic tires, and in particular larger truck and bus radial tires, occasionally will produce a bulge or bump on the outer sidewall surface adjacent the location of the inner body ply splice when inflated. Also, such projections occasionally can occur on the inside of the sidewall before inflation. It has been determined that if this projection exceeds a certain limit above the sidewall surface, the tire should not be used. However, most of these projections do not appear until the tire has been shipped to an installation site and only after the tire is inflated for installation on a vehicle. Thus, it has been difficult for an installer without sophisticated measuring equipment, to easily determine if the projection exceeds the recommended limits since the same is not readily ascertainable by visual sight and/or feel.
Various gauges have been developed for measuring various bumps, projections and/or depressions in tires, most of which use some type of moving member. Examples of such devices are shown in U.S. Pat. Nos. 2,560,571; 3,128,559; 3,645,002; 3,758,957; 4,321,752; 4,653,191; 4,894,920; 5,205,046 and 5,235,988. However, most of these prior art devices are relatively bulky and expensive for producing a sufficient number of them for the service personnel in tire installation shops. Likewise, such devices can be misplaced, lost or damaged at such tire installation sites and are not of sufficient size and weight to be easily carried by a tire installer, such as in a shirt pocket.
Therefore, the need exists for an extremely simple, lightweight, inexpensive device or gauge which can be carried by a tire installer enabling him to rapidly determine the height of any projection appearing on the sidewall of the tire before or after it has been inflated to ensure that it is within the acceptable limits.
The invention provides a height measuring gauge or device formed of an extremely lightweight material such as plastic or aluminum, having a single moving slide or scale for automatically indicating the height of a projection when the device is placed on the sidewall of the tire adjacent the projection.
The device of the invention comprises a U-shaped body having a cross member in which a height indicating scale is slidably mounted for movement between spaced legs of the body upon engagement of a lower end of the sliding scale with the projection.
Another aspect of the invention preferably provides a device in which a slot is formed in the sliding height indicating scale that is engageable with a fixed pin to easily position the scale at the correct location when measuring the sidewall projection without requiring complicated calculations and without the use of springs which are subject to changing characteristics.
Another feature of the invention is to provide such a simple, lightweight, inexpensive device having only a single moving part, which is relatively maintenance free and which eliminates recalibration at any time throughout its life, yet which provides an accurate reading immediately upon placement of the device adjacent a sidewall projection.